Pineal Parenchymal Tumor of Intermediate Differentiation (PPTID)

KEY FACTS

TERMINOLOGY

• Primary parenchymal neoplasm of pineal gland

○ Intermediate in malignancy between pineoblastoma and

pineocytoma

IMAGING

• General features

○ Aggressive-looking pineal mass in adult

○ Extension into adjacent structures (ventricles, thalami) is

common

○ Lobulated, moderately vascular

○ Size varies from small (< 1 cm) to large (~ 6 cm)

• CT

○ Hyperdense mass centered in pineal region

○ Engulfs pineal gland Ca++

○ Hydrocephalus

• MR

○ T1: Mixed iso-/hypointense mass

○ T2: Isointense with gray matter, + small hyperintense foci

○ FLAIR: Hyperintense

○ Strong, heterogeneous enhancement

○ MRS: Elevated Cho, decreased NAA

• If aggressive-looking pineal region tumor in middle-aged,

older adult, consider PPTID

TOP DIFFERENTIAL DIAGNOSES

• Germinoma

• Pineocytoma

• Pineoblastoma

• Papillary tumor of pineal region

PATHOLOGY

• Neuroepithelial neoplasm

○ Arises from pineocytes or their precursors

• WHO grade II or III

CLINICAL ISSUES

• Dorsal midbrain (Parinaud) syndrome, headache

○ Upgaze paralysis, convergence-retraction nystagmus

(Left) Sagittal T1WI MR in a

21-year-old man with

headache shows a pineal

region mass ﬈ with

obstructive hydrocephalus,

enlargement of the 3rd

ventricle ﬇, and cerebellar

tonsillar descent ſt. Imaging

differential considerations

include PPTID, pineoblastoma,

and germinoma. (Right) Axial

T2WI MR shows a very large

PPTID ﬈ with extension into

the ventricular system. Note

the heterogeneous T2

appearance of the mass with

multiple cystic regions ﬇,

typical of PPTID. (Courtesy L.

Loevner, MD.)

(Left) Coronal T1WI C+ MR

shows a large, peripherally

enhancing pineal mass ſt in a

24-year-old man. PPTID was

diagnosed at resection. (Right)

MRs in a 48-year-old woman

shows elevated choline,

decreased NAA, and a lactate

doublet. Imaging is too

aggressive for a pineocytoma.

Germinomas are rare in

middle-aged women. Imaging

is most suggestive of a PPTID,

although a papillary tumor of

the pineal region would be a

possible diagnosis. PPTID was

confirmed at histologic

examination.

Cysts, and Disorders

Brain: Pathology-Based Diagnoses: Neoplasms,

143